To the Editor.—That there are discrepancies between the relative systemic activities of anti-inflammatory steroids in rats and man is well known. In our article "Vasoconstrictor and Systemic Activities of Topical Steroids"1 we were concerned to demonstrate a correlation, if one existed, between systemic activity in animals and topical activity in man. Our results showed that for six of the eight steroids tested, the "ranking orders" for systemic activity in rats and topical activity in man agreed. The exceptions were betamethasone which had a higher and betamethasone 17-valerate which had a lower systemic ranking in rats than would have been expected from their topical activities in man. Dr. Burdick2 states that the topical activity of betamethasone 17-valerate, as measured by several other assays in rats, is also substantially below that of betamethasone and implies that we neglected to give this information in our article. We have